diff options
| -rw-r--r-- | fs/direct-io.c | 111 | ||||
| -rw-r--r-- | include/linux/uio.h | 2 | ||||
| -rw-r--r-- | mm/iov_iter.c | 27 |
3 files changed, 67 insertions, 73 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 387d919..4b410d5 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -77,7 +77,6 @@ struct dio_submit { unsigned blocks_available; /* At block_in_file. changes */ int reap_counter; /* rate limit reaping */ sector_t final_block_in_request;/* doesn't change */ - unsigned first_block_in_page; /* doesn't change, Used only once */ int boundary; /* prev block is at a boundary */ get_block_t *get_block; /* block mapping function */ dio_submit_t *submit_io; /* IO submition function */ @@ -98,19 +97,14 @@ struct dio_submit { sector_t cur_page_block; /* Where it starts */ loff_t cur_page_fs_offset; /* Offset in file */ - /* - * Page fetching state. These variables belong to dio_refill_pages(). - */ - int curr_page; /* changes */ - int total_pages; /* doesn't change */ - unsigned long curr_user_address;/* changes */ - + struct iov_iter *iter; /* * Page queue. These variables belong to dio_refill_pages() and * dio_get_page(). */ unsigned head; /* next page to process */ unsigned tail; /* last valid page + 1 */ + size_t from, to; }; /* dio_state communicated between submission path and end_io */ @@ -163,15 +157,10 @@ static inline unsigned dio_pages_present(struct dio_submit *sdio) */ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) { - int ret; - int nr_pages; + ssize_t ret; - nr_pages = min(sdio->total_pages - sdio->curr_page, DIO_PAGES); - ret = get_user_pages_fast( - sdio->curr_user_address, /* Where from? */ - nr_pages, /* How many pages? */ - dio->rw == READ, /* Write to memory? */ - &dio->pages[0]); /* Put results here */ + ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES * PAGE_SIZE, + &sdio->from); if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) { struct page *page = ZERO_PAGE(0); @@ -186,18 +175,19 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) dio->pages[0] = page; sdio->head = 0; sdio->tail = 1; - ret = 0; - goto out; + sdio->from = 0; + sdio->to = PAGE_SIZE; + return 0; } if (ret >= 0) { - sdio->curr_user_address += ret * PAGE_SIZE; - sdio->curr_page += ret; + iov_iter_advance(sdio->iter, ret); + ret += sdio->from; sdio->head = 0; - sdio->tail = ret; - ret = 0; + sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE; + sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1; + return 0; } -out: return ret; } @@ -208,8 +198,9 @@ out: * L1 cache. */ static inline struct page *dio_get_page(struct dio *dio, - struct dio_submit *sdio) + struct dio_submit *sdio, size_t *from, size_t *to) { + int n; if (dio_pages_present(sdio) == 0) { int ret; @@ -218,7 +209,10 @@ static inline struct page *dio_get_page(struct dio *dio, return ERR_PTR(ret); BUG_ON(dio_pages_present(sdio) == 0); } - return dio->pages[sdio->head++]; + n = sdio->head++; + *from = n ? 0 : sdio->from; + *to = (n == sdio->tail - 1) ? sdio->to : PAGE_SIZE; + return dio->pages[n]; } /** @@ -422,8 +416,8 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) */ static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) { - while (dio_pages_present(sdio)) - page_cache_release(dio_get_page(dio, sdio)); + while (sdio->head < sdio->tail) + page_cache_release(dio->pages[sdio->head++]); } /* @@ -912,23 +906,18 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, struct buffer_head *map_bh) { const unsigned blkbits = sdio->blkbits; - const unsigned blocks_per_page = PAGE_SIZE >> blkbits; - struct page *page; - unsigned block_in_page; int ret = 0; - /* The I/O can start at any block offset within the first page */ - block_in_page = sdio->first_block_in_page; - while (sdio->block_in_file < sdio->final_block_in_request) { - page = dio_get_page(dio, sdio); + struct page *page; + size_t from, to; + page = dio_get_page(dio, sdio, &from, &to); if (IS_ERR(page)) { ret = PTR_ERR(page); goto out; } - while (block_in_page < blocks_per_page) { - unsigned offset_in_page = block_in_page << blkbits; + while (from < to) { unsigned this_chunk_bytes; /* # of bytes mapped */ unsigned this_chunk_blocks; /* # of blocks */ unsigned u; @@ -999,10 +988,9 @@ do_holes: page_cache_release(page); goto out; } - zero_user(page, block_in_page << blkbits, - 1 << blkbits); + zero_user(page, from, 1 << blkbits); sdio->block_in_file++; - block_in_page++; + from += 1 << blkbits; dio->result += 1 << blkbits; goto next_block; } @@ -1020,7 +1008,7 @@ do_holes: * can add to this page */ this_chunk_blocks = sdio->blocks_available; - u = (PAGE_SIZE - offset_in_page) >> blkbits; + u = (to - from) >> blkbits; if (this_chunk_blocks > u) this_chunk_blocks = u; u = sdio->final_block_in_request - sdio->block_in_file; @@ -1032,7 +1020,7 @@ do_holes: if (this_chunk_blocks == sdio->blocks_available) sdio->boundary = buffer_boundary(map_bh); ret = submit_page_section(dio, sdio, page, - offset_in_page, + from, this_chunk_bytes, sdio->next_block_for_io, map_bh); @@ -1043,9 +1031,9 @@ do_holes: sdio->next_block_for_io += this_chunk_blocks; sdio->block_in_file += this_chunk_blocks; - block_in_page += this_chunk_blocks; + from += this_chunk_bytes; + dio->result += this_chunk_bytes; sdio->blocks_available -= this_chunk_blocks; - dio->result += this_chunk_blocks << blkbits; next_block: BUG_ON(sdio->block_in_file > sdio->final_block_in_request); if (sdio->block_in_file == sdio->final_block_in_request) @@ -1054,7 +1042,6 @@ next_block: /* Drop the ref which was taken in get_user_pages() */ page_cache_release(page); - block_in_page = 0; } out: return ret; @@ -1122,7 +1109,6 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, struct dio *dio; struct dio_submit sdio = { 0, }; unsigned long user_addr; - size_t bytes; struct buffer_head map_bh = { 0, }; struct blk_plug plug; unsigned long align = offset | iov_iter_alignment(iter); @@ -1234,6 +1220,10 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, spin_lock_init(&dio->bio_lock); dio->refcount = 1; + sdio.iter = iter; + sdio.final_block_in_request = + (offset + iov_iter_count(iter)) >> blkbits; + /* * In case of non-aligned buffers, we may need 2 more * pages since we need to zero out first and last block. @@ -1250,34 +1240,9 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, blk_start_plug(&plug); - for (seg = 0; seg < iter->nr_segs; seg++) { - user_addr = (unsigned long)iter->iov[seg].iov_base; - sdio.size += bytes = iter->iov[seg].iov_len; - - /* Index into the first page of the first block */ - sdio.first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; - sdio.final_block_in_request = sdio.block_in_file + - (bytes >> blkbits); - /* Page fetching state */ - sdio.head = 0; - sdio.tail = 0; - sdio.curr_page = 0; - - sdio.total_pages = 0; - if (user_addr & (PAGE_SIZE-1)) { - sdio.total_pages++; - bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); - } - sdio.total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; - sdio.curr_user_address = user_addr; - - retval = do_direct_IO(dio, &sdio, &map_bh); - - if (retval) { - dio_cleanup(dio, &sdio); - break; - } - } /* end iovec loop */ + retval = do_direct_IO(dio, &sdio, &map_bh); + if (retval) + dio_cleanup(dio, &sdio); if (retval == -ENOTBLK) { /* diff --git a/include/linux/uio.h b/include/linux/uio.h index b80bbe1..3419861 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -71,6 +71,8 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, unsigned long iov_iter_alignment(const struct iov_iter *i); void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count); +ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, + size_t maxsize, size_t *start); static inline size_t iov_iter_count(struct iov_iter *i) { diff --git a/mm/iov_iter.c b/mm/iov_iter.c index e2c9a2d..45204cd 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -235,3 +235,30 @@ void iov_iter_init(struct iov_iter *i, int direction, i->count = count; } EXPORT_SYMBOL(iov_iter_init); + +ssize_t iov_iter_get_pages(struct iov_iter *i, + struct page **pages, size_t maxsize, + size_t *start) +{ + size_t offset = i->iov_offset; + const struct iovec *iov = i->iov; + size_t len; + unsigned long addr; + int n; + int res; + + len = iov->iov_len - offset; + if (len > i->count) + len = i->count; + if (len > maxsize) + len = maxsize; + addr = (unsigned long)iov->iov_base + offset; + len += *start = addr & (PAGE_SIZE - 1); + addr &= ~(PAGE_SIZE - 1); + n = (len + PAGE_SIZE - 1) / PAGE_SIZE; + res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); + if (unlikely(res < 0)) + return res; + return (res == n ? len : res * PAGE_SIZE) - *start; +} +EXPORT_SYMBOL(iov_iter_get_pages); |
